The present invention relates to a reinforcement element for absorbing forces of concrete slabs in the area of support elements, in particular supports and bearing walls, such slab being equipped with a first flexural reinforcement layer, located adjacent to the support element, and a second flexural reinforcement layer, facing away from the support element, wherein each flexural reinforcement layer is formed essentially by longitudinally and laterally extending reinforcing bars, a number of reinforcement elements being inserted between such flexural reinforcement layers.
Appropriate arrangements have to be made for concrete ceilings or foundation slabs that are supported by supports or on which supports are placed, in order to be able to introduce the supporting forces into the concrete ceilings or foundation slabs in an optimum manner. The shear and punching shear forces in particular must be absorbed, to which the concrete ceilings or foundation slabs are exposed.
For absorbing and introducing these forces into the concrete slabs in the area of the support elements, different solutions have been proposed. One of these proposed solutions, for example, is to insert reinforcement cages as reinforcement elements into the concrete slabs in the area of supports, with such reinforcement cages comprising several juxtaposed U-shaped stirrups that are interconnected by means of cross bars. These reinforcement cages were then inserted in the upper and lower flexural reinforcement layers of the concrete slab and connected to such layers.
These reinforcement cages take up quite a lot of space, storing them and transporting them to the construction site is therefore costly; in addition, loading for the corresponding concrete slabs is limited using such reinforcement cages.
Also known are so-called steel shearheads, which are used in areas of the concrete slabs to be supported. These steel shearheads meet the requirements regarding loading very well, but their disadvantage is that they are very expensive.
Also known are reinforcement elements formed out of reinforcing bars and that are equipped with a base bar with a bracket that is placed on the base bar and connected to it. These reinforcement elements, individually and in the required number, can be inserted into the area of the concrete slab to be supported between the upper and lower flexural reinforcement layer and is connected therewith. A good introduction of the forces into the concrete slab is achieved with these reinforcement elements; however, their handling is still relatively costly, as these reinforcement elements have to be pre-fabricated.
It is desirable to create a reinforcement element for absorbing the forces in concrete slabs in the area of support elements, which not only absorbs large loads but also can be manufactured simply and cheaply while its handling can be very flexible.
According to an aspect of the invention, each reinforcement element is formed out of a longitudinally stable, flexible length element, wherein its first end area is guided through the first flexural reinforcement layer, the first area of such stable, flexible length element that is adjoining the first end area proceeding at an acute angle α towards the second flexural reinforcement layer, the second area that is adjoining the first area being guided through the second flexural reinforcement layer and proceeding, in the area of the support element, along the surface of the second flexural reinforcement layer, which is facing away from the support element, and the second end area of such stable, flexible length element being guided through the second flexural reinforcement layer towards the first flexural reinforcement layer.
The longitudinally stable, flexible length element, through which the reinforcement elements are formed, can, for example, be brought to the construction site in a coil, the reinforcement elements can be uncoiled from this coil, and cut to the desired length; the required numbers of this longitudinally stable, flexible length element can then be easily laid between and through the first and second flexural reinforcement layer; the concrete slab that is reinforced in such a way can be supported in an optimum manner.
Advantageously, the longitudinally stable, flexible length element has the form of a band, wherein its width is a multiple of its thickness and which can be cut to the desired length. This length element can be inserted into the flexural reinforcement layers in an optimum manner. This band, of course, can be formed from a plurality of individual strands, which can be arranged next to each other and/or one on top of the other. This band can also be formed from one individual strand, which has loops at the end areas and is laid on top of itself in multiple layers.
Advantageously, several longitudinally and laterally extending reinforcement elements are each inserted into the concrete slab essentially parallel to the appropriate longitudinally and laterally extending reinforcing bars of the first flexural reinforcement layer and the second flexural reinforcement layer, wherein the number of the reinforcement elements depends on the loads to be absorbed and can be determined accordingly.
An additional advantageous embodiment of an aspect of the Invention is that the reinforcement elements are inserted into the concrete slab in multiple layers. Thus, the use of the reinforcement elements can be adapted in a very flexible way to the forces to be absorbed.
An additional advantageous embodiment of an aspect of the Invention is that the first and the second end areas and/or the first areas of the reinforcement elements, which are set in multilayers into the concrete slab, extending toward and away from one another, by which an optimum load distribution can be achieved, depending on the mode of application.
Advantageously, the angle α is in the range of 20° to 50°, enabling an optimum transfer of the forces to be absorbed.
An additional advantageous embodiment of an aspect of the invention is in that the longitudinally stable, flexible length element is formed out of carbon fibre reinforced plastics, by which the desired physical properties are achieved in an optimum manner.
An additional advantageous embodiment of an aspect of the invention is in that the second end area is guided into the first flexural reinforcement layer in accordance with the first end area for middle support elements for the concrete slab to be supported. By means of the symmetric arrangement, the forces are introduced optimally into the concrete slab.
The end areas of the reinforcement elements are each guided around at least one laterally extending reinforcing bar of the first flexural reinforcement layer, while the second area is guided across the appropriate laterally extending reinforcing bars of the second flexural reinforcement layer. This also results in an optimum introduction of the forces by means of the reinforcement elements to the flexural reinforcement layers.
An additional advantageous embodiment of an aspect of the invention is in that the edge supports of the slab can be supported, the second end area is guided against the support element to the first flexural reinforcement layer. The longitudinally stable, flexible length element forming the reinforcement element is suitable in an optimum way for any application.
The improvement of the anchoring of the end areas of the reinforcement elements in concrete slabs can be achieved in different ways: the end areas can be looped over several laterally extending reinforcing bars of the first flexural reinforcement layer; however, the end areas of the reinforcement elements can also be equipped with anchoring means serving as anchoring elements, adapted to the respective types of application.
Advantageously, saddle elements are fitted on the laterally extending reinforcing bars around which the reinforcement elements are diverted, with such saddle elements protecting the reinforcement elements in these areas.
An additional advantageous embodiment of an aspect of the invention is in that the reinforcement elements can be inserted in existing slabs in the area of support elements, for which drill holes can be applied to the slab to be reinforced, through which holes the respective reinforcement element can be inserted, and that the drill holes can be filled and the end areas can be held with anchoring elements. Existing constructions can thus also be reinforced in an optimum manner with the same reinforcement elements.
In this case as well, in the area of the redirections of the reinforcement elements, saddle elements can be inserted into the drill holes, the reinforcement elements are supported on such saddle elements, by which means the reinforcement elements are protected from damage here as well.